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Stanley J. Roux - One of the best experts on this subject based on the ideXlab platform.
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Generation of Transgenic Spores of the Fern Ceratopteris richardii to Analyze Ca 2+ Transport Dynamics During Gravity-Directed Polarization
Current Advances in Fern Research, 2018Co-Authors: Ashley E. Cannon, Mari L. Salmi, Araceli Cantero, Stanley J. RouxAbstract:Spores from the fern, Ceratopteris richardii, have been used to study gravity-directed cell polarization for over three decades. This system is ideal for these studies because it has a highly predictable growth and developmental pattern and primarily responds to the mechanical force of gravity during polarization. Early studies on the development in this system showed that during the first 24 h of germination, Ceratopteris spores establish a Ca2+ concentration differential along the outer periphery of the cell that is defined by the uptake of Ca2+ through channels at the bottom of the spore and an efflux of Ca2+ through pumps at the top. This 100-fold [Ca2+] differential is sensitive to the direction and magnitude of the gravitational force. In a low-gravity environment or when the uptake of Ca2+ is blocked, spore polarization becomes random. These results support the hypothesis that the uptake of Ca2+ is necessary for gravity-directed polarization in Ceratopteris spores. For many years, studies of Ceratopteris were limited by the inability to produce stable transformants. However, recent protocols have led to the first stably transformed lines in Ceratopteris richardii. This work reviews and discusses the latest studies of gravity-induced changes in Ca2+ transport dynamics in Ceratopteris spores, the use of transformation protocols to overexpress or knock out genes relevant to the transport of Ca2+ in Ceratopteris, and the potential value of mutants to more thoroughly understand the role of Ca2+ transport dynamics in gravity-directed polarization of spores.
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Studying molecular changes during gravity perception and response in a single cell
Methods in molecular biology (Clifton N.J.), 2015Co-Authors: Ashley E. Cannon, Thomas J. Bushart, Mari L. Salmi, Stanley J. RouxAbstract:Early studies revealed a highly predictable pattern of gravity-directed growth and development in Ceratopteris richardii spores. This makes the spores a valuable model system for the study of how a single cell senses and responds to the force of gravity. Gravity regulates both the direction and magnitude of a trans-cell calcium current in germinating spores, and the orientation of this current predicts the polarization of spore development. Molecular techniques have been developed to evaluate the transcriptomic and proteomic profiles of spores before and after gravity establishes the polarity of their development. Here we describe these techniques, along with protocols for sterilizing the spores, sowing them in a solid or liquid growth media, and evaluating germination.
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Structure and function of CrACA1, the major PM-type Ca2+-ATPase, expressed at the peak of the gravity-directed trans-cell calcium current in spores of the fern Ceratopteris richardii
Plant Biology, 2013Co-Authors: Thomas J. Bushart, Ashley E. Cannon, Greg Clark, Stanley J. RouxAbstract:Spores of the fern Ceratopteris richardii have proven to be a valuable single-cell system for studying gravity responses. The earliest cellular change directed by gravity in these cells is a trans-cell calcium current, which peaks near 10 h after the spores are induced to germinate. This current is needed for gravity-directed axis alignment, and its peak is coincident with the time period when gravity polarises the direction of subsequent nuclear migration and rhizoid growth. Transcriptomic analysis of genes expressed at the 10-h time point revealed several that encode proteins likely to be key components that either drive the current or regulate it. Notable among these is a plasma membrane (PM)-type Ca(2+) ATPase, CrACA1, whose activity pumping Ca(2+) out of cells is regulated by gravity. This report provides an initial characterisation of the structure and expression of this protein, and demonstrates its heterologous function complementing the K616 mutant of yeast, which is deficient in PM-type Ca(2+) pump activity. Gravity-induced changes in the trans-cell Ca(2+) current occur within seconds, a result consistent with the hypothesis that the force of gravity can rapidly alter the post-translational state of the channels and pumps that drive this current across spore cells. This report identifies a transporter likely to be a key driver of the current, CrACA1, and characterises the role of this protein in early germination and gravity-driven polarity fixation through analysis of expression levels, functional complementation and pharmacological treatments. These data, along with newly available transcriptomic data obtained at the 10-h time point, indicate that CrACA1 is present, functional and likely a major contributing component of the trans-cell Ca(2+) efflux. CrACA1 is not necessary for polar axis alignment, but pharmacological perturbations of it disrupt rhizoid development. These data support and help refine the post-translational modification model for gravity responses.
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Cellular, Molecular, and genetic changes during the development of Ceratopteris richardii gametophytes
Working with Ferns, 2010Co-Authors: Mari L. Salmi, Thomas J. Bushart, Stanley J. RouxAbstract:Ceratopteris richardii is an aquatic fern that has proven to be a productive model system for studies in the genetics, biochemistry, and cell biology of early gametophytic development. Here we review and discuss the recent literature that documents the cellular, molecular, and gene expression changes that occur in gametophytes during polarity development and sexual differentiation, and in response to the environmental stimuli of light and gravity. Different approaches to achieve genetic transformation in this fern will also be discussed.
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TESTING THE ROLE OF CA2+-ATPASES IN THE GRAVITY-DIRECTED, TRANS-CELL CURRENT OF CALCIUM IN SINGLE-CELLED SPORES OF Ceratopteris richardii
Gravitational and Space Research, 2010Co-Authors: Thomas J. Bushart, Greg Clark, D. Marshall Porterfiled, Stanley J. RouxAbstract:Spores of the fern Ceratopteris richardii are useful models for studying molecular components of the gravity response in single cells. They feature a polar calcium flux that is determined by the gravity vector (Chatterjee et al., 2000). Recent data using calcium-selective electrodes and silicon microfabricated sensor arrays (unpublished data) indicate that gravity can induce rapid changes in the direction and magnitude of a trans-cell Ca2+ current in these spores within hours after light induces them to begin germinating. Here we examine the role of calcium transport in the early germination and growth of spores of the C. richardii system.
Dale L. Vogelien - One of the best experts on this subject based on the ideXlab platform.
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Sodium/potassium selectivity and pleiotropy in stl2, a highly salt‐tolerant mutation of Ceratopteris richardii
Plant Cell & Environment, 1999Co-Authors: Thomas R. Warne, Leslie G. Hickok, Carl E. Sams, Dale L. VogelienAbstract:The roles of Na+ and K+ (Rb+) uptake were further studied in a NaCl-tolerant strain of Ceratopteris richardii containing the stl2 mutation by direct comparison with the wild-type strain. In addition to Na+ tolerance, stl2 also confers tolerance to Mg2+ and sensitivity to K+. In addition to higher K+ (Rb+) uptake at concentrations commonly associated with low-affinity K+ transport, stl2 maintained higher uptake down to 0·1 mol m–3 Rb+. Up to a 25-fold excess of Na+ had little effect in either genotype on K+ (Rb+) uptake at low concentrations, i.e. 0·2 and 0·5 mol m–3 RbCl. Pretreatment with K+ (20 mol m–3) inhibited uptake of K+ (Rb+) in the wild type, whereas concurrent inclusion of K+ inhibited uptake of Rb+ more in stl2. In the absence of K+, Na+ uptake (0·01–60 mol m–3) was nearly identical in the wild type and stl2. K+ inhibited Na+ uptake more effectively in stl2 than the wild type, especially at 60 mol m–3 Na+. Greater inhibition of K+ uptake in stl2 occurred with MgCl2 or TEA (tetraethylammonium chloride) preincubation or with simultaneous inclusion of Al3+ (Al2SO4). The higher effective velocity of K+ uptake at a wide range of concentrations and the enhanced selectivity for K+ and against Na+ contribute to the preservation of higher cytosolic K+ and lower Na+ under salinity stress.
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sodium potassium selectivity and pleiotropy in stl2 a highly salt tolerant mutation of Ceratopteris richardii
Plant Cell and Environment, 1999Co-Authors: Thomas R. Warne, Leslie G. Hickok, Carl E. Sams, Dale L. VogelienAbstract:The roles of Na+ and K+ (Rb+) uptake were further studied in a NaCl-tolerant strain of Ceratopteris richardii containing the stl2 mutation by direct comparison with the wild-type strain. In addition to Na+ tolerance, stl2 also confers tolerance to Mg2+ and sensitivity to K+. In addition to higher K+ (Rb+) uptake at concentrations commonly associated with low-affinity K+ transport, stl2 maintained higher uptake down to 0·1 mol m–3 Rb+. Up to a 25-fold excess of Na+ had little effect in either genotype on K+ (Rb+) uptake at low concentrations, i.e. 0·2 and 0·5 mol m–3 RbCl. Pretreatment with K+ (20 mol m–3) inhibited uptake of K+ (Rb+) in the wild type, whereas concurrent inclusion of K+ inhibited uptake of Rb+ more in stl2. In the absence of K+, Na+ uptake (0·01–60 mol m–3) was nearly identical in the wild type and stl2. K+ inhibited Na+ uptake more effectively in stl2 than the wild type, especially at 60 mol m–3 Na+. Greater inhibition of K+ uptake in stl2 occurred with MgCl2 or TEA (tetraethylammonium chloride) preincubation or with simultaneous inclusion of Al3+ (Al2SO4). The higher effective velocity of K+ uptake at a wide range of concentrations and the enhanced selectivity for K+ and against Na+ contribute to the preservation of higher cytosolic K+ and lower Na+ under salinity stress.
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High Salinity Tolerance in the stl2 Mutation of Ceratopteris richardii is Associated with Enhanced K+ Influx and Loss
Plant Cell and Environment, 1996Co-Authors: Thomas R. Warne, Leslie G. Hickok, Thomas B. Kinraide, Dale L. VogelienAbstract:The roles of K + uptake and loss in the salinity response of the wild type and the salt-tolerant mutant stl2 of Ceratopteris richardii were studied by measuring Rb + influx and loss and the effects of Na + , Mg 2+ , Ca 2+ and K + -transport inhibitors. In addition, electrophysiological responses were measured for both K + and Rb + and for the effects of Na + and NH 4 + on subsequent K + -induced depolarizations. stl2 had a 26-40% higher uptake rate for Rb + than the wild type at 0.5-10 mol m -3 RbCl. Similarly, membrane depolarizations induced by both RbCl and KCl were consistently greater in stl2. In the presence of 0-180 mol m -3 NaCl, stl2 maintained a consistently greater Rb + influx than the wild type. stl2 retained a greater capacity for subsequent KCl-induced depolarization following exposure to NaCl. Five mol m -3 Mg 2+ decreased Rb + uptake in stl2 ; however, additional Mg 2+ up to 40 mol m -3 did not affect Rb + uptake further. Ca 2+ supplementation resulted in a very minor decrease of Rb + uptake that was similar in the two genotypes. Tetraethylammonium chloride and CsCl gave similar inhibition of Rb + uptake in both genotypes, but NH 4 Cl gave substantially greater inhibition in the wild type than in stl2. NH 4 Cl resulted in a greater membrane depolarization in the wild type and the capacity for subsequent depolarization by KCl was markedly reduced. stl2 exhibited a higher K + -dependent loss of Rb + than the wild type, but, in the absence of external K + , loss of Rb + was equivalent in the two genotypes. Since constitutive K + contents are nearly identical, we conclude that high K + influx and loss exact a metabolic cost that is reflected in the inhibition of gametophytic growth. Growth inhibition can be alleviated by reduced supplemental K + or by treatments that slightly reduce K + influx, such as moderate concentrations of Na + or Mg 2+ . We propose that high throughput of K + allows maintenance of cytosolic K + under salt stress and that a high uptake rate for K + results in a reduced capacity for the entrance and accumulation of alternative cations such as Na + in the cytosol.
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Differential effects of Na+, Mg2+, K+, Ca2+ and osmotic stress on the wild type and the NaCl-tolerant mutants stl1 and stl2 of Ceratopteris richardii
Plant Cell and Environment, 1996Co-Authors: Dale L. Vogelien, Leslie G. Hickok, Thomas R. WarneAbstract:In order to identify physiological components that contribute to salinity tolerance, we compared the effects of Na + , Mg 2+ and K + salts (NaCl, Na 2 SO 4 , MgCl 2 , MgSO 4 , KCl and K 2 SO 4 ), Ca 2+ (CaSO 4 ), mannitol and melibiose on the wild type and the single-gene NaCl-tolerant mutants stl1 and stl2 of Ceratopteris richardii. Compared with gametophytic growth of the wild type, stl2 showed a low level of tolerance that was restricted to Na + salts and osmotic stress. stl2 exhibited high tolerance to both Na + and Mg 2+ salts, as well as to osmotic stress. In response to short-term exposure (3 d) to NaCl, accumulation of K + and Na + was similar in the wild type and stl1. In contrast, stl2 accumulated higher levels of K + and lower levels of Na + . Ca 2+ supplementation (1.0 mol m -3 ) ameliorated growth inhibition by Na + and Mg 2+ stress in wild type and stll, but not in stl2. In addition, under Na + stress (175 mol m -3 ) wild-type, stl1 and stl2 gametophytes maintained higher tissue levels of K + and lower levels of Na + when supplemented with Ca 2+ (1.0 mol m -3 ). stl2 gametophytes were extremely sensitive to K + supplementation. Growth of stl2 was greater than or equal to that of the wild type at trace concentrations of K + but decreased substantially with increasing K + concentration. Supplementation with K + from 0 to 1.85 mol m -3 alleviated some of the inhibition by 75 mol m -3 NaCl in the wild type and in stl1. In stl2, growth at 75 mol m -3 NaCl was similar at 0 and 1.85 mol m -3 K + supplementation. Although K + supplementation above 1.85 mol m -3 did not alleviate inhibition of growth by Na + in any genotype, stl2 maintained greater relative tolerance to NaCl at all K + concentrations tested.
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differential effects of na mg2 k ca2 and osmotic stress on the wild type and the nacl tolerant mutants stl1 and stl2 of Ceratopteris richardii
Plant Cell and Environment, 1996Co-Authors: Dale L. Vogelien, Leslie G. Hickok, Thomas R. WarneAbstract:In order to identify physiological components that contribute to salinity tolerance, we compared the effects of Na + , Mg 2+ and K + salts (NaCl, Na 2 SO 4 , MgCl 2 , MgSO 4 , KCl and K 2 SO 4 ), Ca 2+ (CaSO 4 ), mannitol and melibiose on the wild type and the single-gene NaCl-tolerant mutants stl1 and stl2 of Ceratopteris richardii. Compared with gametophytic growth of the wild type, stl2 showed a low level of tolerance that was restricted to Na + salts and osmotic stress. stl2 exhibited high tolerance to both Na + and Mg 2+ salts, as well as to osmotic stress. In response to short-term exposure (3 d) to NaCl, accumulation of K + and Na + was similar in the wild type and stl1. In contrast, stl2 accumulated higher levels of K + and lower levels of Na + . Ca 2+ supplementation (1.0 mol m -3 ) ameliorated growth inhibition by Na + and Mg 2+ stress in wild type and stll, but not in stl2. In addition, under Na + stress (175 mol m -3 ) wild-type, stl1 and stl2 gametophytes maintained higher tissue levels of K + and lower levels of Na + when supplemented with Ca 2+ (1.0 mol m -3 ). stl2 gametophytes were extremely sensitive to K + supplementation. Growth of stl2 was greater than or equal to that of the wild type at trace concentrations of K + but decreased substantially with increasing K + concentration. Supplementation with K + from 0 to 1.85 mol m -3 alleviated some of the inhibition by 75 mol m -3 NaCl in the wild type and in stl1. In stl2, growth at 75 mol m -3 NaCl was similar at 0 and 1.85 mol m -3 K + supplementation. Although K + supplementation above 1.85 mol m -3 did not alleviate inhibition of growth by Na + in any genotype, stl2 maintained greater relative tolerance to NaCl at all K + concentrations tested.
Thomas R. Warne - One of the best experts on this subject based on the ideXlab platform.
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Sodium/potassium selectivity and pleiotropy in stl2, a highly salt‐tolerant mutation of Ceratopteris richardii
Plant Cell & Environment, 1999Co-Authors: Thomas R. Warne, Leslie G. Hickok, Carl E. Sams, Dale L. VogelienAbstract:The roles of Na+ and K+ (Rb+) uptake were further studied in a NaCl-tolerant strain of Ceratopteris richardii containing the stl2 mutation by direct comparison with the wild-type strain. In addition to Na+ tolerance, stl2 also confers tolerance to Mg2+ and sensitivity to K+. In addition to higher K+ (Rb+) uptake at concentrations commonly associated with low-affinity K+ transport, stl2 maintained higher uptake down to 0·1 mol m–3 Rb+. Up to a 25-fold excess of Na+ had little effect in either genotype on K+ (Rb+) uptake at low concentrations, i.e. 0·2 and 0·5 mol m–3 RbCl. Pretreatment with K+ (20 mol m–3) inhibited uptake of K+ (Rb+) in the wild type, whereas concurrent inclusion of K+ inhibited uptake of Rb+ more in stl2. In the absence of K+, Na+ uptake (0·01–60 mol m–3) was nearly identical in the wild type and stl2. K+ inhibited Na+ uptake more effectively in stl2 than the wild type, especially at 60 mol m–3 Na+. Greater inhibition of K+ uptake in stl2 occurred with MgCl2 or TEA (tetraethylammonium chloride) preincubation or with simultaneous inclusion of Al3+ (Al2SO4). The higher effective velocity of K+ uptake at a wide range of concentrations and the enhanced selectivity for K+ and against Na+ contribute to the preservation of higher cytosolic K+ and lower Na+ under salinity stress.
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sodium potassium selectivity and pleiotropy in stl2 a highly salt tolerant mutation of Ceratopteris richardii
Plant Cell and Environment, 1999Co-Authors: Thomas R. Warne, Leslie G. Hickok, Carl E. Sams, Dale L. VogelienAbstract:The roles of Na+ and K+ (Rb+) uptake were further studied in a NaCl-tolerant strain of Ceratopteris richardii containing the stl2 mutation by direct comparison with the wild-type strain. In addition to Na+ tolerance, stl2 also confers tolerance to Mg2+ and sensitivity to K+. In addition to higher K+ (Rb+) uptake at concentrations commonly associated with low-affinity K+ transport, stl2 maintained higher uptake down to 0·1 mol m–3 Rb+. Up to a 25-fold excess of Na+ had little effect in either genotype on K+ (Rb+) uptake at low concentrations, i.e. 0·2 and 0·5 mol m–3 RbCl. Pretreatment with K+ (20 mol m–3) inhibited uptake of K+ (Rb+) in the wild type, whereas concurrent inclusion of K+ inhibited uptake of Rb+ more in stl2. In the absence of K+, Na+ uptake (0·01–60 mol m–3) was nearly identical in the wild type and stl2. K+ inhibited Na+ uptake more effectively in stl2 than the wild type, especially at 60 mol m–3 Na+. Greater inhibition of K+ uptake in stl2 occurred with MgCl2 or TEA (tetraethylammonium chloride) preincubation or with simultaneous inclusion of Al3+ (Al2SO4). The higher effective velocity of K+ uptake at a wide range of concentrations and the enhanced selectivity for K+ and against Na+ contribute to the preservation of higher cytosolic K+ and lower Na+ under salinity stress.
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High Salinity Tolerance in the stl2 Mutation of Ceratopteris richardii is Associated with Enhanced K+ Influx and Loss
Plant Cell and Environment, 1996Co-Authors: Thomas R. Warne, Leslie G. Hickok, Thomas B. Kinraide, Dale L. VogelienAbstract:The roles of K + uptake and loss in the salinity response of the wild type and the salt-tolerant mutant stl2 of Ceratopteris richardii were studied by measuring Rb + influx and loss and the effects of Na + , Mg 2+ , Ca 2+ and K + -transport inhibitors. In addition, electrophysiological responses were measured for both K + and Rb + and for the effects of Na + and NH 4 + on subsequent K + -induced depolarizations. stl2 had a 26-40% higher uptake rate for Rb + than the wild type at 0.5-10 mol m -3 RbCl. Similarly, membrane depolarizations induced by both RbCl and KCl were consistently greater in stl2. In the presence of 0-180 mol m -3 NaCl, stl2 maintained a consistently greater Rb + influx than the wild type. stl2 retained a greater capacity for subsequent KCl-induced depolarization following exposure to NaCl. Five mol m -3 Mg 2+ decreased Rb + uptake in stl2 ; however, additional Mg 2+ up to 40 mol m -3 did not affect Rb + uptake further. Ca 2+ supplementation resulted in a very minor decrease of Rb + uptake that was similar in the two genotypes. Tetraethylammonium chloride and CsCl gave similar inhibition of Rb + uptake in both genotypes, but NH 4 Cl gave substantially greater inhibition in the wild type than in stl2. NH 4 Cl resulted in a greater membrane depolarization in the wild type and the capacity for subsequent depolarization by KCl was markedly reduced. stl2 exhibited a higher K + -dependent loss of Rb + than the wild type, but, in the absence of external K + , loss of Rb + was equivalent in the two genotypes. Since constitutive K + contents are nearly identical, we conclude that high K + influx and loss exact a metabolic cost that is reflected in the inhibition of gametophytic growth. Growth inhibition can be alleviated by reduced supplemental K + or by treatments that slightly reduce K + influx, such as moderate concentrations of Na + or Mg 2+ . We propose that high throughput of K + allows maintenance of cytosolic K + under salt stress and that a high uptake rate for K + results in a reduced capacity for the entrance and accumulation of alternative cations such as Na + in the cytosol.
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Differential effects of Na+, Mg2+, K+, Ca2+ and osmotic stress on the wild type and the NaCl-tolerant mutants stl1 and stl2 of Ceratopteris richardii
Plant Cell and Environment, 1996Co-Authors: Dale L. Vogelien, Leslie G. Hickok, Thomas R. WarneAbstract:In order to identify physiological components that contribute to salinity tolerance, we compared the effects of Na + , Mg 2+ and K + salts (NaCl, Na 2 SO 4 , MgCl 2 , MgSO 4 , KCl and K 2 SO 4 ), Ca 2+ (CaSO 4 ), mannitol and melibiose on the wild type and the single-gene NaCl-tolerant mutants stl1 and stl2 of Ceratopteris richardii. Compared with gametophytic growth of the wild type, stl2 showed a low level of tolerance that was restricted to Na + salts and osmotic stress. stl2 exhibited high tolerance to both Na + and Mg 2+ salts, as well as to osmotic stress. In response to short-term exposure (3 d) to NaCl, accumulation of K + and Na + was similar in the wild type and stl1. In contrast, stl2 accumulated higher levels of K + and lower levels of Na + . Ca 2+ supplementation (1.0 mol m -3 ) ameliorated growth inhibition by Na + and Mg 2+ stress in wild type and stll, but not in stl2. In addition, under Na + stress (175 mol m -3 ) wild-type, stl1 and stl2 gametophytes maintained higher tissue levels of K + and lower levels of Na + when supplemented with Ca 2+ (1.0 mol m -3 ). stl2 gametophytes were extremely sensitive to K + supplementation. Growth of stl2 was greater than or equal to that of the wild type at trace concentrations of K + but decreased substantially with increasing K + concentration. Supplementation with K + from 0 to 1.85 mol m -3 alleviated some of the inhibition by 75 mol m -3 NaCl in the wild type and in stl1. In stl2, growth at 75 mol m -3 NaCl was similar at 0 and 1.85 mol m -3 K + supplementation. Although K + supplementation above 1.85 mol m -3 did not alleviate inhibition of growth by Na + in any genotype, stl2 maintained greater relative tolerance to NaCl at all K + concentrations tested.
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differential effects of na mg2 k ca2 and osmotic stress on the wild type and the nacl tolerant mutants stl1 and stl2 of Ceratopteris richardii
Plant Cell and Environment, 1996Co-Authors: Dale L. Vogelien, Leslie G. Hickok, Thomas R. WarneAbstract:In order to identify physiological components that contribute to salinity tolerance, we compared the effects of Na + , Mg 2+ and K + salts (NaCl, Na 2 SO 4 , MgCl 2 , MgSO 4 , KCl and K 2 SO 4 ), Ca 2+ (CaSO 4 ), mannitol and melibiose on the wild type and the single-gene NaCl-tolerant mutants stl1 and stl2 of Ceratopteris richardii. Compared with gametophytic growth of the wild type, stl2 showed a low level of tolerance that was restricted to Na + salts and osmotic stress. stl2 exhibited high tolerance to both Na + and Mg 2+ salts, as well as to osmotic stress. In response to short-term exposure (3 d) to NaCl, accumulation of K + and Na + was similar in the wild type and stl1. In contrast, stl2 accumulated higher levels of K + and lower levels of Na + . Ca 2+ supplementation (1.0 mol m -3 ) ameliorated growth inhibition by Na + and Mg 2+ stress in wild type and stll, but not in stl2. In addition, under Na + stress (175 mol m -3 ) wild-type, stl1 and stl2 gametophytes maintained higher tissue levels of K + and lower levels of Na + when supplemented with Ca 2+ (1.0 mol m -3 ). stl2 gametophytes were extremely sensitive to K + supplementation. Growth of stl2 was greater than or equal to that of the wild type at trace concentrations of K + but decreased substantially with increasing K + concentration. Supplementation with K + from 0 to 1.85 mol m -3 alleviated some of the inhibition by 75 mol m -3 NaCl in the wild type and in stl1. In stl2, growth at 75 mol m -3 NaCl was similar at 0 and 1.85 mol m -3 K + supplementation. Although K + supplementation above 1.85 mol m -3 did not alleviate inhibition of growth by Na + in any genotype, stl2 maintained greater relative tolerance to NaCl at all K + concentrations tested.
Leslie G. Hickok - One of the best experts on this subject based on the ideXlab platform.
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The effects of light on sex determination in gametophytes of the fern Ceratopteris richardii
Journal of Plant Research, 2007Co-Authors: Hiroyuki Kamachi, Munenori Noguchi, Leslie G. Hickok, Orie Iwasawa, Masaaki Nakayama, Hiroshi InoueAbstract:The sexuality of homosporous fern gametophytes is usually determined by antheridiogen, a pheromone that promotes maleness. In this work the effect of photomorphogenically active light on antheridiogen-induced male development was examined for gametophytes of Ceratopteris richardii . Although blue light did not affect sensitivity to Ceratopteris antheridiogen (A_Ce) in wild-type gametophytes, it was found that the gametophytes of the her1 mutant, which are insensitive to A_Ce, developed into males when grown under blue light in the presence of A_Ce. Thus, we conclude that another A_Ce-signal transduction pathway activated by blue light exists latently in the gametophytes of C. richardii . Red light, on the other hand, suppressed male development. Because simultaneous red and blue light-irradiation did not promote male development in the her1 gametophytes, the action of red light seems to dominate that of blue light. The results of experiments with a photomorphogenic mutant also suggested that phytochrome may be involved in the action of red light.
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Characterization of the sleepy sperm mutant in the fern Ceratopteris richardii: A new model for the study of axonemal function
Canadian Journal of Botany, 2004Co-Authors: Karen S. Renzaglia, Kelly Davidson Wood, Gerald Rupp, Leslie G. HickokAbstract:Structural and motility characteristics of the zzz1 "sleepy sperm" mutant of Ceratopteris richardii Brongn. are described using scanning electron, transmission electron, light, and fluorescence microscopy. Although the zzz1 phenotype segregates as the product of a single gene mutation, the expression of the mutation varies within a single haploid gametophyte. The majority of mutant sperm cells are slow to initiate motility and typically swim in a slow, spiraling pattern. However, motility phenotypes range from immotile to wild-type (normal). This variable phenotypic expression is associated with a wide range of defects in the microtubule systems, especially the flagellar axonemes and the spline, a structure that provides a structural backbone for the cell. Defects in the spline microtubule array are associated with atypical cell shape and organellar positioning. Axonemal aberrations include an absence of the central pair complex and clumped flagella. We hypothesize that the gene product encoded by the zzz...
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Microscopic Characterization of a Sperm Mutant Line of the Fern Ceratopteris richardii
Microscopy and Microanalysis, 2000Co-Authors: Kelly A. Davidson, Leslie G. Hickok, Karen S. RenzagliaAbstract:Mature sperm cells of Ceratopteris richardii are spiraled over three revolutions and contain a locomotory apparatus with approximately 70 flagella attached at the cell anterior (Fig. 1). Abundant organelles are dispersed along the inner surface of an elongated, coiled nucleus (Figs. 1, 3, 8). The cytoskeleton comprises a network of microfilaments that encases the nucleus (Fig. 6) and two distinct microtubule arrays: a microtubular ribbon (spline) and flagella with anchoring basal bodies (Fig. 3). This study uses light, fluorescence, transmission electron (TEM), and scanning electron microscopy (SEM) to characterize cell organization in a motility impaired sperm mutant line of Ceratopteris. Because motility mutations likely involve the cytoskeleton, emphasis was placed on observing microtubule and actin arrays in the mutant compared to wild-type sperm cells. Protocols follow Hoffman and Vaughn for TEM and Schmitt and Renzaglia for SEM. Microfilament arrays in relation to the nucleus were examined by rhodamine-phalloidin and DAPI fluorescence.
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Multiple ribosomal RNA gene loci in the genome of the homosporous fern Ceratopteris richardii
Canadian Journal of Botany, 1999Co-Authors: J. Mitchell Mcgrath, Leslie G. HickokAbstract:The genomes of homosporous ferns are largely uncharacterized, but they appear to differ from gymnosperms and angiosperms in key aspects, such as high chromosome numbers at the diploid level, and thus provide a unique perspective on plant genome structure and evolution. Using the model homosporous fern Ceratopteris richardii, loci encoding ribosomal RNA sequences (rDNA genes) were detected using fluorescent in situ hybridization. At least two major rDNA loci were visible in all cases, and six or more weakly hybridizing signals were observed in most cytological preparations. These results are consistent with models of homosporous fern evolution via cycles of polyploidy followed by gene silencing. They are also consistent with other models of fern genome evolution. With the exception of the weakly hybridizing signals, these data are similar to analogous reports of one or two major rDNA loci in diploid angiosperms. These results suggest that the gross morphology of rDNA loci are similar between diploid homosp...
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Sodium/potassium selectivity and pleiotropy in stl2, a highly salt‐tolerant mutation of Ceratopteris richardii
Plant Cell & Environment, 1999Co-Authors: Thomas R. Warne, Leslie G. Hickok, Carl E. Sams, Dale L. VogelienAbstract:The roles of Na+ and K+ (Rb+) uptake were further studied in a NaCl-tolerant strain of Ceratopteris richardii containing the stl2 mutation by direct comparison with the wild-type strain. In addition to Na+ tolerance, stl2 also confers tolerance to Mg2+ and sensitivity to K+. In addition to higher K+ (Rb+) uptake at concentrations commonly associated with low-affinity K+ transport, stl2 maintained higher uptake down to 0·1 mol m–3 Rb+. Up to a 25-fold excess of Na+ had little effect in either genotype on K+ (Rb+) uptake at low concentrations, i.e. 0·2 and 0·5 mol m–3 RbCl. Pretreatment with K+ (20 mol m–3) inhibited uptake of K+ (Rb+) in the wild type, whereas concurrent inclusion of K+ inhibited uptake of Rb+ more in stl2. In the absence of K+, Na+ uptake (0·01–60 mol m–3) was nearly identical in the wild type and stl2. K+ inhibited Na+ uptake more effectively in stl2 than the wild type, especially at 60 mol m–3 Na+. Greater inhibition of K+ uptake in stl2 occurred with MgCl2 or TEA (tetraethylammonium chloride) preincubation or with simultaneous inclusion of Al3+ (Al2SO4). The higher effective velocity of K+ uptake at a wide range of concentrations and the enhanced selectivity for K+ and against Na+ contribute to the preservation of higher cytosolic K+ and lower Na+ under salinity stress.
Jo Ann Banks - One of the best experts on this subject based on the ideXlab platform.
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sex determination in Ceratopteris richardii is accompanied by transcriptome changes that drive epigenetic reprogramming of the young gametophyte
G3: Genes Genomes Genetics, 2018Co-Authors: Nadia M Atallah, Olga Vitek, Federico Gaiti, Milos Tanurdzic, Jo Ann BanksAbstract:The fern Ceratopteris richardii is an important model for studies of sex determination and gamete differentiation in homosporous plants. Here we use RNA-seq to de novo assemble a transcriptome and identify genes differentially expressed in young gametophytes as their sex is determined by the presence or absence of the male-inducing pheromone called antheridiogen. Of the 1,163 consensus differentially expressed genes identified, the vast majority (1,030) are up-regulated in gametophytes treated with antheridiogen. GO term enrichment analyses of these DEGs reveals that a large number of genes involved in epigenetic reprogramming of the gametophyte genome are up-regulated by the pheromone. Additional hormone response and development genes are also up-regulated by the pheromone. This C. richardii gametophyte transcriptome and gene expression dataset will prove useful for studies focusing on sex determination and differentiation in plants.
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2013Co-Authors: Olivier Leroux, Sharon Eeckhout, Ronald L. L. Viane, Madelaine Elisabeth Bartlett, Jo Ann BanksAbstract:Ceratopteris richardii (C-Fern): a model for investigatin
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gametophyte development in ferns
Annual review of plant physiology and plant molecular biology, 1999Co-Authors: Jo Ann BanksAbstract:▪ Abstract The fern gametophyte has interested plant biologists for the past century because its structure and development is simple and amenable to investigation. Past studies have described many aspects of its development, including germination of the spore, patterns of cell division and differentiation, photomorphogenic or light-regulated responses, sex determination and differentiation of gametangia, hormone and pheromone responses, and fertilization. Several genes that are predicted to regulate some of these processes have been recently cloned, making it possible to analyze how these processes are controlled at a molecular level. The emergence of the fern Ceratopteris richardii as a model organism for readily identifying and characterizing mutations that affect key developmental processes in gametophytes makes it a powerful tool for dissecting the molecular mechanisms underlying these processes. If advances in gene cloning techniques and transformation are forthcoming in Ceratopteris, it is likely th...
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Characterization of homeodomain-leucine zipper genes in the fern Ceratopteris richardii and the evolution of the homeodomain-leucine zipper gene family in vascular plants.
Molecular biology and evolution, 1999Co-Authors: K Aso, Jo Ann Banks, Masahiro Kato, Mitsuyasu HasebeAbstract:The homeodomain-leucine zipper (HD-Zip) genes encode transcription factors that are characterized by the presence of both a homeodomain and a leucine zipper motif. They belong to the homeobox gene superfamily and have been reported only from flowering plants. This article is the first report on the ferm HD-Zip genes (named Crhb1-Crhb11) isolated from the homosporous ferm Ceratopteris richardii. Phylogenetic analyses of the II Crhb genes with previously reported angiosperm HD-Zip genes show that the Crhb genes belong to three of the four different angiosperm HD-Zip subfamilies (HD-Zip I, II, and IV), indicating that these subfamilies of HD-Zip genes originated before the diversification of the ferm and seed plant lineages. The Crhb4-Crhb8 and Crhb11 genes belong to the HD-Zip I subfamily but differ from angiosperm HD-Zip I genes by the presence of a seven-amino-acid indel in the leucine zipper motif. By the northern analyses, Crhb1 and Crhb3 were expressed only in gametophyte tissue. Expression of Crhb2 and Crhb11 genes could not be detected in any tissue examined, while all other Crhb genes were expressed in most sporophytic and gametophytic tissues. Although the functions of the Crhb genes in Ceratopteris are unknown, their patterns of expression suggest that they regulate developmental or physiological processes common to both the gametophyte and the sporophyte generations of the fern. Differences in the expression of Crhb1 between male gametophytes and male-hermaphrodite mixed populations of gametophytes suggests that the Crhb1 gene is involved in gametophytic sex determination.
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Characterization of MADS homeotic genes in the fern Ceratopteris richardii
Proceedings of the National Academy of Sciences of the United States of America, 1998Co-Authors: Mitsuyasu Hasebe, Chi-kuang Wen, Masahiro Kato, Jo Ann BanksAbstract:The MADS genes encode a family of transcription factors, some of which control the identities of floral organs in flowering plants. To understand the role of MADS genes in the evolution of floral organs, five MADS genes (CMADS1, 2, 3, 4, and 6) were cloned from the fern Ceratopteris richardii, a nonflowering plant. A gene tree of partial amino acid sequences of seed plant and fern MADS genes showed that the fern genes form three subfamilies. All members of one of the fern MADS subfamilies have additional amino-terminal amino acids, which is a synapomorphic character of the AGAMOUS subfamily of the flowering plant MADS genes. Their structural similarity indicates a sister relationship between the two subfamilies. The temporal and spatial patterns of expression of the five fern MADS genes were assessed by Northern blot analyses and in situ hybridizations. CMADS1, 2, 3, and 4 are expressed similarly in the meristematic regions and primordia of sporophyte shoots and roots, as well as in reproductive structures, including sporophylls and sporangial initials, although the amount of expression in each tissue is different in each gene. CMADS6 is expressed in gametophytic tissues but not in sporophytic tissues. The lack of organ-specific expression of MADS genes in the reproductive structures of the fern sporophyte may indicate that the restriction of MADS gene expression to specific reproductive organs and the specialization of MADS gene functions as homeotic selector genes in the flowering plant lineage were important in floral organ evolution.